Class LazyInitializedCacheMap<K,V>

This map is specially useful when reads are much more frequent than writes and
if the cost of instantiating the values is high like allocating an
IoBuffer for example.
Based on the final implementation of Memoizer written by Brian Goetz and Tim
Peierls. This implementation will return an
UnsupportedOperationException on each method that is not intended to
be called by user code for performance reasons.